Field
Exemplary embodiments of the present disclosure relate to a sedimentation tank and a water treatment apparatus including the same, and a high-rate sedimentation tank capable of quickly removing a floc formed by flocculating foreign materials, etc., included in raw water (stream water, effluent from a sewage treatment plant, etc.) as sludge and a water treatment apparatus including the same.
Description of the Related Art
Various pollutants of turbidity causing materials, chromaticity, THM precursor, microorganism including algae, etc., such as suspended solids and colloid contained in raw water, are adsorbed to hydrates generated by hydration reaction of flocculants, thereby generating a micro floc. A water treatment process of generating the micro floc as a good macro floc with good sedimentation is flocculation and sedimentation as a next process to remove the generated floc under the water is needed.
Meanwhile, cross section structures of a circular sedimentation tank and a gravitational rectangular sedimentation tank which may be used in the sedimentation are each illustrated in FIGS. 1 and 2. That is, the typical sedimentation tank 1 illustrated in FIG. 1 is configured to include a wear 2 formed at an inner circumference of an upper end thereof to discharge supernatant, a lower inclined surface 3 collecting deposited sludge, a scraper 5 adhering to the inclined surface 3 and including a rotating shaft rotated by a motor 4, a sludge discharger 6 for removing the collected sludge, and a center well 8 mounted at an upper center thereof and introduced with influent to discharge the influent down and mounted with an intake pipe 7. A lower portion of the center well 8 is opened, and as a result, the influent introduced into the center wall 8 is introduced into the sedimentation tank 1 through the opened lower end of the center well 8 and then the sludge is sunk and the supernatant rises to be discharged through the wear 2.
Meanwhile, the gravitational rectangular sedimentation tank 10 illustrated in FIG. 2 is configured to include a hopper part of an upstream side at which the sludge is deposited and a bottom inclined part of a downstream side at which a vertical distance between a bottom surface and a water surface is narrow toward downstream. Further, in the hopper part of the upstream side, a vertical baffle 20 provided with a plurality of inlets 21 is installed on a side surface vertically meeting a flow of the influent. On the other hand, the inclined portion of the downstream side is provided with a scratch type sludge collector 30 driven by a motor and an upper end of a wall surface is provided with an outflow weir 40. The hopper part and the upstream side of the bottom inclined part are provided with a sedimentary layer (that is, a sludge layer) of naturally deposited sludge and sludge collected from the bottom of the inclined part to the sludge collector 30.
However, the typical sedimentation tank needs to continuously use a mechanical scraper to remove the sludge deposited at the lower portion of the sedimentation tank, and therefore installation cost and maintenance cost of the water processing system may be increased and the sedimentation generally requires four hours or more. In particular, the rectangular sedimentation tank requires a large scale site for installation.
Therefore, the development of a sedimentation tank capable of operating sedimentation without power, performing high-rate sedimentation, and minimizing a site area has been required recently.